I have installed Sendinblue extension in order to manage my email marketing with it. I've been working with Sendinblue for 1 year and everything was fine... till now.
The thing is that when I install the extension, it lets me send my transactional email with them. As "yes" is the default option, we tried this. The result is that around 30% of my trasnactional emails are not sent. These orders in magento appear with the text "the confirmation email has not been sent" in theses cases. Also, these emails does'nt appear on the log at Sendinblue.
The first thing I though was: well, I don't need Sendinblue to work with transactional emails, I just want it for email marketing. So, I turned off the "send trasnactional emails with Sendinblue" option. After that, I recieved none of my transactional emails. 0%. But the orders say "the confirmation order has been sent".
I've been in contact with Sendinblue but their responses are absolutely lame. "You must have something on your Magento that doesn't work". I uninstalled the extension and everything is working fine again.So yes, the thing that wasn't working was your extension.
Do you have any clue about what's happening? If i cannot set my sendinblue extension, I will need to find another partner .